Urethane press

ABSTRACT

A press for moulding urethane consists of a platform surmounted by a plurality of rolls spaced apart from the platform, a distance slightly less than the height of the mould, the latter being forced between the platform and rolls by means of a hydraulic ram.

[22] Filed:

United States Patent Roloff [s41 URETHANE PRESS [72] lnventor: Walter Louis Roloff, Listowel, On-

tario, Canada [73] Assignee: The Andrew Malcolm Furniture Co.,

Limited March 16, 1970 [21] Appl. No.: 19,665

521 U.S.Cl. ..425/410, 100/144, 100/237, 100/265, 100/295 51 Int. Cl ..B29c 3/00 [58] FieldofSearch ..18/16 R, 16 E, 16 F, 161-1, 18/43, 5 P; 100/265, 295, 144, 237; 425/352,

[56] References Cited UNITED STATES PATENTS 3,391,658 7/ 1968 Williams ..99/349 UX [1 1 3,685,944 [451 Aug.22, 1972 3,325,861 6/ 1967 Pincus et a1. 18/5 P 618,375 l/1899 Bump ..100/l44 3,117,513 l/1964 Burnett et al. ..l00/218 X 2,815,051 12/1957 Spanhel et al. 100/295 Primary Examiner-Robert L. Spicer, .lr.

Attorney-Douglas S. Johnson [57] ABSTRACT A press for moulding urethane consists of a platform surmounted by a plurality of rolls spaced apart from the platform, a distance slightly less than the height of the mould, the latter being forced between the platform and rolls by means of a hydraulic ram.

3 Claim, 5 Drawing Figures PATENTEUmzz m2 3.685. 944

' sum 2 or 3 I N EN TOR.

WALTER ROLOFF URETHANE PRESS FIELD OF THE INVENTION This invention relates to the moulding of articles made from liquid plastic. It has particular relation to the production of articles, for instance parts of fumiture, made from liquid urethane to which a catalyst has been added for the purpose of setting.

PRIOR ART:

In recent years there has been a marked increase in the use of moulded urethane parts in furniture construction which urethane parts replace one's formerly made of carved wood, such parts for instance being chair backs, door panels, etc. The parts are formed in moulds into which is poured liquid urethane which incorporates a catalyst. The moulds are made of silicone rubber, the surface of which has been previously shaped to simulate the carved wood forms which the moulded plastic parts are intended to replace. The flexible silicone rubber mould is supported in a holder which may be made of wood or metal. The mould has a cover which forms a seal with the holder at the contacting edges.

It is a characteristic of the urethane to which a catalyst has been added that after pouring into the mould it expands during setting, and hence it is necessary to provide-suitable means to maintain the cover in position over the mould and in continued contact with the holder. It has been the practice to achieve closure by means of bolts or clamps, but since considerable pressure is exerted by the liquid urethane during the setting stage, frequently the cover becomes separated from the mould holder with the result that the urethane escapes, thus spoiling the shape of the moulded form.

Furthermore, after the liquid urethane has been poured into the mould, only a short period of time elapses before expansion, associated with the setting, takes place. The time which elapses depends on the nature of the catalyst and the temperature of the urethane, but it can be as little as one minute, and the clamps or bolts have to be applied within this time; otherwise it is impossible to place the mould cover into position.

An object of the invention is to provide apparatus which eliminates the use of clamps or bolts in order to keep the cover in place on the mould holder, and which also enables the requisite pressure to be applied to the mould over the whole period of setting, which is approximately fifteen minutes.

SUMMARY OF THE INVENTION:

The apparatus of the invention consists of a platform which is surmounted by a plurality of members, each of which is spaced apart from the platform a distance slightly less than the distance between the top of the mould cover and the bottom of the mould holder when the two are brought together in edge contact. The assembled mould is forced between the space between the platform and the surmounting members by means of a hydraulic ram; further movement of the mould along the platform is achieved by the action of following moulds fed in by the ram. Pressure means capable of adjustment operate on the platform and the members to maintain their spaced relationship, thus ensuring that the requisite pressure is supplied to the mould during the setting period. The platform with its surmounting members is of such a length that pressure does not terminate on the moving mould until the setting period has elapsed.

BRIEF DESCRIPTION OF THE DRAWINGS:

The invention will now be described in relation to the accompanying drawings in which:

FIG. 1 is a side view of apparatus constructed according to one embodiment of the invention;

FIG. 2 is an end view taken on lines 2-2 of FIG. 1;

FIG. 3 is an enlarged perspective view of the spring loaded platens which bear onto the mould cover;

FIG. 4 is a section of apparatus according to a further embodiment of the invention;

FIG. 5 is a cross-section taken on Lines 55 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

With reference to the drawings it will be appreciated that the side and end views opposed to FIGS. 1 and 2 respectively will be the same and hence like numbers indicate like parts. The apparatus is supported on spaced apart end pairs of upright stanchions 12 and 14; both end pairs of stanchions l2 and 14 are connected by lower and upper crossbeams 16 and 18. To complete the support structure stanchions 12 and 14 are joined at each side of the apparatus by overlapping stiffening bars 20 and 22.

The lower crossbeam 16 supports a pair of spaced apart beams 24 which run between the end pairs of stanchions 12 and 14. The spaced apart beams 24 in turn support a smooth platform 26 which extends outward of the stanchions 14 as shown.

Each upper crossbeam 18 has a pair of spaced apart open-ended tubular vertical extensions 28, each containing the upper end of a downwardly depending coil spring 30. Each of the upper crossbeams 18 also has a pair of spaced apart outwardly extending internally threaded abutments 32, each containing an individual downwardly extending threaded rod 34 with an accompanying nut 36; the vertical position of the threaded rod 34 is arranged by rotation of the nut 36 and its engagement with the underside of the abuunent 32.

Surmounting the platform 26 and spaced therefrom are a pair of spaced apart I-beams 38. The lower and upper flanges 40 and 42 of each I-beam 38 lie in corresponding horizontal planes. The upper flange 42 of each I-beam 38 is secured to the lower end of a pair of the coil springs 30 thereby providing for support of the respective I-beam 38. The upper flange 42 of each I- beam 38 is also secured to the lower end of a pair of the threaded rods 34; it will be appreciated that the spaced apart relationship of the I-beams 38 with respect to the platform 26 may be adjusted by rotation of the nuts 36 on the threaded rods 34.

Adjacent the outward extension of the platform 26 is a hydraulically operated horizontally disposed piston 44 which rides in a cylinder 46. The outer end of the piston 44 has a cross bar 48, the lower edge of which just clears the upper surface of the extension of the platform 26.

The moulds 50 consist of a lower mould holder 52, conveniently constructed of wood, and having on its underside a pair of runners 54; the mould holder 52 contains a silicone rubber mould 56. Surmounting the mould holder 52 is a sealing cover 58, the upper surface of which has a pair of runners 60.

In the embodiment shown in FIG. 3 the lower flange 40 of each of the beams 38 has secured thereto a series of spaced apart cross plates 62, which are held in place by downwardly extending bolts 64 and accompanying nuts 66. Extending through the lower flange 40 and each cross plate 62 are a pair of rods 68, the lower ends of which are secured to a platen 70, of which there are a series in spaced apart relationship, each in line with a respective cross plate 62, but spaced therefrom. A coil spring 72 surrounds each rod 68 to bear against a plate 62 and the respective platen 70. The rods 68 are moveable in the cross plate 62 and the lower flange 42 of the beam 40 and are suspended by bolts 76.

The position of each platen 70 in relation to the others is preserved by means of a chain 78 with suitable bolts 80 passing through a selected link of the chain 78 where it crosses over the individual platen 70.

The operation of the apparatus is as follows: the silicone rubber mould 56, supported in the lower mould holder 52 is filled with the liquid urethane and the requisite catalyst after which the sealing cover 58 is placed over the mould holder 52. The mould 50 is then placed on the extension of platform 26 after which the piston is operated so as to bring the cross bar 48 into contact with the mould 50. Further extension of the piston 44 propels the mould 50 into the restricted between the nearest platen 70 and the platform 26.

The distance between the platens 70 and the platform 26 may be adjusted by the rotation of the nuts 36 on the threaded rods 34, thereby varying the pressure which is necessary to maintain the sealing relationship of the sealing cover 58 and the mould holder 52. To assist in the entry of the mould 50 between the platen 70 and platform 26, the mould may be bevelled at its leading edges. Additional moulds 50 are filled with liquid urethane and propelled by means of the piston 44 into the space between the platen and the platform 26 thus forcing the moulds already under pressure along the entire length of the platform 26.

An alternative arrangement is illustrated in FIGS. 4 and 5 wherein the spring loaded platens 70 are replaced by a series of transverse rollers which are joumalled in the web 82 of the I-beams 84. In this arrangement, which provides less drag on the moulds 50, it has been found advisable to provide other pressure means apart from the threaded rods 34. This additional pressure means comprises opposed bars 86 and 88 which operate on the underside and the top respectively of the beams 24 and the I-beams 38, the cross beams 86 and 88 being connected by threaded rods 90 and nuts 92.

The apparatus described provides the requisite pressure to maintain the sealing cover 58 in sealing relationship with the mould holder 52 and the mould 50, and also enables the mould 50 to be brought under the requisite pressure in a matter of seconds after the mould has been filled with the liquid urethane.

What I claim as my invention is:

1. Apparatus for applying sealing pressure to a mold formed of a detachable sealing cover located on a mold holder, said mold containin an expansible setting liquid mixture of urethane an a catalyst and resting on a platform, successive pressure means above said platform and arranged to bear on said mold, when in contact therewith, and ram means for propelling said mold along said platform when said mold is in contact with said pressure means for successive contact therewith, said ram means bearing against the end of said mold and moving the same along said platform towards said pressure means.

2. Apparatus according to claim 1 wherein said successive pressure means are a series of spring loaded platens.

3. Apparatus according to claim 1 wherein said pressure means are a plurality of rollers. 

1. Apparatus for applying sealing pressure to a mold formed of a detachable sealing cover located on a mold holder, said mold containing an expansible setting liquid mixture of urethane and a catalyst and resting on a platform, successive pressure means above said platform and arranged to bear on said mold, when in contact therewith, and ram means for propelling said mold along said platform when said mold is in contact with said pressure means for successive contact therewith, said ram means bearing against the end of said mold and moving the same along said platform towards said pressure means.
 2. Apparatus according to claim 1 wherein said successive pressure means are a series of spring loaded platens.
 3. Apparatus according to claim 1 wherein said pressure means are a plurality of rollers. 